Media monitoring using multiple types of signatures

ABSTRACT

Media monitoring using multiple types of signatures is disclosed. Example methods disclosed herein include, in response to determining that a media signature of a first type reported by a device meter matched a reference signature of the first type associated with first reference media, sending a first indication to the device meter to indicate that media monitored by the device meter corresponds to the first reference media, and sending a set of reference signatures of a second type associated with the first reference media to the device meter. Disclosed example methods also include receiving a second indication from the device meter indicating that the media monitored by the device meter no longer corresponds to the first reference media, and in response to receiving the second indication, processing subsequent media signatures of the first type reported by the device meter to identify the media being monitored by the device meter.

RELATED APPLICATION(S)

This patent arises from a continuation of U.S. patent application Ser.No. 14/800,317 (now U.S. Pat. No. ______), which is entitled “MEDIAMONITORING USING MULTIPLE TYPES OF SIGNATURES,” and which was filed onJul. 15, 2015, which is a continuation of U.S. patent application Ser.No. 14/299,794 (now U.S. Pat. No. 9,106,952), which is entitled “MEDIAMONITORING USING MULTIPLE TYPES OF SIGNATURES,” and which was filed onJun. 9, 2014, which is a continuation of U.S. patent application Ser.No. 13/430,342 (now U.S. Pat. No. 8,768,003), which is entitled “MEDIAMONITORING USING MULTIPLE TYPES OF SIGNATURES,” and which was filed onMar. 26, 2012. U.S. patent application Ser. No. 13/430,342, U.S. patentapplication Ser. No. 14/299,794 and U.S. patent application Ser. No.14/800,317 are hereby incorporated by reference in their respectiveentireties.

FIELD OF THE DISCLOSURE

This disclosure relates generally to media monitoring and, moreparticularly, to media monitoring using multiple types of signatures.

BACKGROUND

An audience measurement system typically includes one or more devicemeters to monitor the media presented by one or more media deviceslocated at one or more monitored sites. Such a device meter can usewatermarks decoded from the presented media or signatures (also referredto as media fingerprints) generated from the presented media, or both,to monitor (e.g., identify and track) the media being presented by amedia device. When signatures are used for media monitoring, signaturesof the monitored media (referred to herein as collected signatures ormonitored signatures) are generated by the device meter and compared toreference signatures representative of reference media known to theaudience measurement system. For media monitoring applications in whichthe amount of reference media for comparison is large, correspondinglylarge signatures (e.g., having high resolution) are usually needed toaccurately identify the monitored media within a reasonable time period.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an example audience measurement system thatsupports media monitoring using multiple types of signatures asdisclosed herein.

FIG. 2 is a block diagram of an example meter that can be used toimplement the example audience measurement system of FIG. 1.

FIG. 3 is a block diagram of an example signature processor that can beused to implement the example meter of FIG. 2.

FIG. 4 is a block diagram of an example data facility processor that canbe used to implement the example audience measurement system of FIG. 1.

FIG. 5 is a flowchart representative of example machine readableinstructions that may be executed to implement the example audiencemeasurement system of FIG. 1.

FIG. 6 is a flowchart representative of first example machine readableinstructions that may be executed to implement the example meter of FIG.2 and/or that may be used to perform meter processing in the examplemachine readable instructions of FIG. 5.

FIG. 7 is a flowchart representative of second example machine readableinstructions that may be executed to implement the example meter of FIG.2 and/or that may be used to perform meter processing in the examplemachine readable instructions of FIG. 5.

FIG. 8 is a flowchart representative of first example machine readableinstructions that may be executed to implement the example data facilityprocessor of FIG. 4 and/or that may be used to perform data facilityprocessing in the example machine readable instructions of FIG. 5.

FIG. 9 is a flowchart representative of second example machine readableinstructions that may be executed to implement the example data facilityprocessor of FIG. 4 and/or that may be used to perform data facilityprocessing in the example machine readable instructions of FIG. 5.

FIG. 10 is a flowchart representative of example machine readableinstructions that may be executed to implement signature intervaladjustment in the example meter of FIG. 2 and/or the example signatureprocessor of FIG. 3.

FIG. 11 is a block diagram of an example processing system that mayexecute the example machine readable instructions of FIGS. 5-9 and/or 10to implement the example meter of FIG. 2, the example signatureprocessor of FIG. 3, the example data facility processor of FIG. 4and/or the example audience measurement system of FIG. 1.

DETAILED DESCRIPTION

Media monitoring using multiple types of signatures is disclosed herein.As noted above, an audience measurement system can use media signaturesto identify/monitor media being presented by a media device. In such anaudience measurement system, monitored signatures are generated from themonitored media and compared with reference signatures representative ofreference media known to the audience measurement system. As also notedabove, large signatures, which correspond to high resolution signatures,also referred to herein as rich signatures, may be needed to accuratelyand quickly identify the monitored media when the amount of referencemedia for comparison is large. However, it may be impractical (e.g., interms of cost, memory, bandwidth, etc.) to use such large signatures toperform continuous monitoring of the media presented by a monitoredmedia device. Thus, prior media identification techniques that employlarge, rich signatures to quickly perform a single identification of aparticular media presentation may not be applicable to media monitoringapplications involving continuous media device monitoring.

In contrast, media monitoring in accordance with the examples disclosedherein uses multiple types of signatures for media monitoring toovercome the impracticalities of prior, single-type signature-basedsystems, at least in some examples. For example, a first type ofsignature (e.g., a larger, rich signature) can be used by exampledisclosed audience measurement systems to initially identify (e.g.,quickly) a monitored media presentation from among a potentially largeamount of reference media. Then, after the monitored media has beeninitially identified, a second type of signature (e.g., a smaller, lowerresolution signature) can be used by the audience measurement systemsfor continuous monitoring of the media presentation, at least until themedia changes. In some examples, the first type of signature (e.g., thelarger, high resolution signature) and the second type of signature(e.g., the smaller, low resolution signature) can be derived from thesame signature algorithm, whereas in other examples, the first andsecond types of signatures are derived from different signaturealgorithms. In the event that the media being presented by monitoredmedia device changes, example disclosed audience measurement systems canrevert to using the first type of signature (e.g., the larger, richsignature) to initially identify (e.g., quickly) this new mediapresentation, followed again by using the second type of signature(e.g., the smaller, lower resolution signature) to perform continuousmonitoring.

Accordingly, example media monitoring methods disclosed herein includeprocessing monitored signatures (also referred to as collectedsignatures) of a first type to monitor media presented by a media deviceuntil a first one of the monitored signatures of the first type isdetermined to match a reference signature of the first type. Thereference signature of the first type is associated with first referencemedia (e.g., from among a group of reference media that may include themonitored media being presented by the media device). The examplemethods also include using monitored signatures of a second type tomonitor the media presented by the media device after the first one ofthe monitored signatures of the first type is determined to match thereference signature of the first type and until a number of monitoredsignatures of the second type is determined not to match correspondingreference signatures of the second type. The reference signatures of thesecond type are also associated with the first reference media (e.g.,which is the same reference media associated with the matching referencesignature of the first type).

In some examples, the methods further include reverting to using themonitored signatures of the first type to monitor the media presented bythe media presentation device when the number of monitored signatures ofthe second type is determined not to match the corresponding referencesignatures of the second type. As noted above and described in greaterdetail below, in some examples, the signatures of the first type have ahigher resolution (e.g., and, thus, are larger) than the signatures ofthe second type. Additionally or alternatively, in some examples, themethods adjust an interval between the monitored signatures of thesecond type based on one or more characteristics of the media presentedby the media device.

Further example media monitoring methods, example apparatus to implementmedia monitoring using multiple types of signatures, and examplearticles of manufacture (e.g., storage media) storing machine readableinstructions which, when executed, cause example machine(s) to performmedia monitoring using multiple types of signatures, are also disclosedherein.

Turning to the figures, a block diagram of an example audience meteringsystem 100 employing media monitoring using multiple types of signaturesas disclosed herein is illustrated in FIG. 1. The example audiencemeasurement system 100 supports monitoring of media exposure toaudiences at one or more monitored sites, such as the example monitoredsite 105 illustrated in FIG. 1. The monitored site 105 includes anexample media device 110, which is also referred to herein as a mediapresentation device 110. Although the example of FIG. 1 illustrates onemonitored site 105 and one media device 110, media monitoring usingmultiple types of signatures as disclosed herein can be used in audiencemeasurement systems 100 supporting any number of monitored sites 105having any number of media devices 110.

The audience measurement system 100 of the illustrated example includesan example device meter 125, also referred to as a site meter 125, asite unit 125, a home unit 125, etc., to monitor media presented by themedia device 110. In the illustrated example, the device meter 125determines metering data that may identify and/or be used to identifymedia exposure at the monitored site 105. The audience measurement meter125 then stores and reports this metering data via an example network135 to an example data processing facility 140. The data processingfacility 140 performs any appropriate post-processing of the audiencemeasurement data to, for example, determine audience ratingsinformation, identify targeted advertising to be provided to themonitored site 105, etc. In the illustrated example, the network 130 cancorrespond to any type(s) and/or number of wired and/or wireless datanetworks, or any combination thereof.

In the illustrated example, the media device 110 monitored by the devicemeter 125 can correspond to any type of audio, video and/or multimediapresentation device capable of presenting media audibly and/or visually.For example, the media device 110 can correspond to a television and/ordisplay device that supports the National Television Standards Committee(NTSC) standard, the Phase Alternating Line (PAL) standard, the SystemeElectronique pour Couleur avec Memoire (SECAM) standard, a standarddeveloped by the Advanced Television Systems Committee (ATSC), such ashigh definition television (HDTV), a standard developed by the DigitalVideo Broadcasting (DVB) Project, etc. As another example, the mediadevice 110 can correspond to a multimedia computer system, a personaldigital assistant, a cellular/mobile smartphone, a radio, a tablet, etc.

In the audience measurement system 100 of the illustrated example, thedevice meter 125 and the data processing facility 140 cooperate toperform media monitoring using multiple types of signatures as disclosedherein. Unlike media monitoring techniques based on codes and/orwatermarks included with and/or embedded in the monitored media,signature-based media monitoring techniques generally use one or moreinherent characteristics of the monitored media during a monitoring timeinterval to generate a substantially unique proxy for the media. Such aproxy is referred to as a signature or signature, and can take the formof a series of digital values, a waveform, etc., representative of themedia signal(s), such as the audio and/or video signals, forming themedia presentation being monitored. A good signature is usually one thatis repeatable when processing the same media presentation, but that isunique when processing other presentations of other media.

Signature-based media monitoring generally involves determining (e.g.,generating) monitored signature(s) (also referred to as collectedsignature(s)) representative of a media signal (e.g., an audio signaland/or a video signal) output by a monitored media device and comparingthe monitored signature(s) to one or more references signaturescorresponding to known (e.g., reference) media sources. Variouscomparison criteria, such as a cross-correlation value, a Hammingdistance, etc., can be evaluated to determine whether a monitoredsignature matches a particular reference signature. When a substantialmatch between the monitored signature and one of the referencesignatures is found, the monitored media can be identified ascorresponding to the particular reference media source represented bythe reference signature that substantially matched the monitoredsignature. Because attributes, such as an identifier of the media, apresentation time, a broadcast channel, etc., are collected for thereference signature, these attributes may then be associated with themonitored media whose monitored signature matched the referencesignature.

For example, in the audience measurement system 100 of FIG. 1, thedevice meter 125 may utilize invasive monitoring involving one or morephysical connections to the media device 110, and/or non-invasivemonitoring not involving any physical connection to the media device110, to obtain access to one or more media signals corresponding to themedia being presented by the media device 110. In some examples, thedevice meter 125 may process audio signals obtained from the mediadevice 110 via a microphone and/or a direct cable connection to generatemonitored audio signatures representative of the media being presentedby the media device 110. Additionally or alternatively, the device meter125 may process video signals obtained from the media device 110 via acamera and/or a direct cable connection to generate monitored videosignatures (e.g., image signatures) representative of the media beingpresented by the media device 110. The device meter 125 and/or the dataprocessing facility 140 then compare the monitored signatures generatedby the device meter 125 with known reference signatures toidentify/monitor the media being presented by the media device 110.

Furthermore, unlike prior signature-based media monitoring techniques,the device meter 125 and the data processing facility 140 of the exampleaudience measurement system 100 employ multiple types of signatures tomonitor the media being presented by the media device 110. For example,a first type of signature, such as a larger, higher resolution (e.g.,rich) signature, can be used by the device meter 125 and the dataprocessing facility 140 to initially identify the media being presentedby the monitored media device 110. Then, after the monitored media isinitially identified, a second type of signature, such as a smaller,lower resolution (e.g., light) signature, can be used by the devicemeter 125 and the data processing facility 140 to continue monitoring ofthe media being presented by the monitored media device 110. Use of sucha lower resolution signature is advantageous as it lowers the processingand/or bandwidth requirements for the device(s) generating thesignatures, transmitting the signatures, receiving the signatures,and/or performing the signature matching, thereby supporting continuousmedia monitoring with negligible (e.g., little to no) loss in accuracy.Furthermore, in at least some examples, the audience measurement system100 can support real time media rating applications because the audiencemeasurement system 100 can quickly identify the monitored media using,for example, high resolution signatures, and then perform continuous,efficient real-time monitoring using, for example, lower resolutionsignatures, which may utilize less processing power for signaturematching than is utilized when matching the high resolution signatures.

In some examples, the interval at which the device meter 125 samples themedia signal(s) forming the monitoring media presentation to generatethe monitored signatures is varied depending on the characteristic(s) ofthe media signal(s), as described in greater detail below. Also, in theevent that the media being presented by the media device 110 laterchanges (e.g., such as when a commercial advertisement is presentedduring a program broadcast, or due to a channel change, selection of adifferent media source, accessing of different online/on-demand media, avolume change, etc., any of which could be detected by, for example,infrared/wireless commands from a remote control device that areintercepted by the device meter 125) or the second type of signatureotherwise is no longer able to accurately identify/monitor the presentedmedia, the device meter 125 and the data processing facility 140 canrevert to using the first type of signature to identify the new mediabeing presented by the monitored media device 110. This process of usingthe first and second types of signatures then repeats to enable the newmedia being presented by the monitored media device 110 to beidentified/monitored in an efficient and consistent manner. In someexample, further types of signatures can be employed the device meter125 and/or the data processing facility 140 for media monitoring toprovide further granularity for switching among using signatures havingdifferent sizes, resolution characteristics, etc.

In some examples, to initially identify the media being presented by themedia device 110 using a first type of signature (e.g., a highresolution signature), the device meter 125 samples and processes mediasignal(s) (e.g., an audio signal and/or a video signal) forming themonitored media presentation to collect (e.g., generate) monitoredsignatures (e.g., monitored audio signatures and/or monitored videosignatures) of the first type (e.g., high resolution or otherwise richsignatures) that are representative of the media presentation. Thedevice meter 125 then reports the monitored signatures of the firsttype, via the network 135, to the data processing facility 140. The dataprocessing facility 140, in turn, receives the monitored signatures ofthe first type from the device meter 125 and compares the monitoredsignatures to a collection of reference signatures of the first type. Inthe illustrated example, the collection of reference signatures isrepresentative of a collection of reference media that is known to thedata processing facility 140. When at least one of the monitoredsignatures of the first type is determined to match (e.g., substantiallymatch within a tolerance, threshold, etc.) a reference signature of thefirst type, the data processing facility 140 associates the mediamonitored at the monitored site 105 with the particular reference mediacorresponding to the matching reference signature. The data processingfacility 140 also sends a success indication to the device meter 125 toindicate that a match between the reported monitored signatures and thereference signatures of the first type has been found.

After the media being presented by the media device 110 is identifiedusing the signatures of the first type (e.g., as indicated by thesuccess indication sent by the data processing facility 140 and receivedby the device meter 125), the device meter 125 switches to collecting(e.g., generating) monitored signatures (e.g., monitored audiosignatures and/or monitored video signatures) of a second type (e.g.,low resolution or otherwise light signatures) that are alsorepresentative of the media presentation. These monitored signatures ofthe second type are then compared to a sequence of reference signaturesof the second type that are associated with the particular referencemedia corresponding to the matching signatures of the first type. Insome examples, the monitored and reference signatures of the second typeare representative of media segments sampled sequentially from therespective monitored and reference media. Also, in some of examples, thesequence of reference signatures of the second type is selected to havea starting reference signature that is representative of a referencemedia segment corresponding to a time or anchor point in the referencemedia that also corresponds to the reference signature of the first typethat was determined to match the monitored signatures of the first typepreviously reported by the device meter 125. In other words, the anchorpoint in the reference media that corresponds to the reference mediasegment represented by the matching reference signature of the firsttype also defines the start of the sequence of reference signatures ofthe second type that are to be used for subsequent (e.g., continuous)monitoring of the media being presented by the media device 110.

In some examples, the device meter 125 reports the monitored signaturesof the second type to the data processing facility 140 for comparisonwith the sequence of reference signatures of the second type. In suchexamples, generation, reporting and comparison of the signatures of thesecond type continues until the data processing facility 140 determinesthat a number of monitored signature(s) of the second type have failedto match the corresponding reference signature (s) in the sequence ofreference signatures of the second type. When such a match failure isdetected, the data processing facility 140 sends a match failureindication to the device meter 125 to indicate that the monitoredsignature(s) of the second type are no longer adequately matching thesequence of reference signature of the second type. This match failureindication also indicates that the monitored media presentation at thesite 105 no longer corresponds to the previously identified referencemedia, thereby causing the device meter 125 to revert to using thesignatures of the first type to identify the new media being presentedby the media device 110.

In some examples, such as when the network 135 provides a high-speedInternet connection or an otherwise high bandwidth connection from thedata processing facility 140 to the device meter 125, at least some ofthe signature comparison processing can be performed at the device meter125 instead of the data processing facility 140. Such a paradigm shiftcan reduce the processing load and associated costs at the dataprocessing facility 140 in favor of spreading the processing to thedevice meter(s) 125, which can potentially reduce overall costs in theaudience measurement system 100. For example, after the media beingpresented by the media device 110 is identified using the signatures ofthe first type (e.g., as indicated by the success indication sent by thedata processing facility 140 and received by the device meter 125), thedata processing facility 140 can further send, to the device meter 125,sequence(s) of reference signatures of the second type to be used insubsequent (e.g., continuous) monitoring of the media being presented bythe media device 110. As noted above, the start of the sequence ofreference signatures of the second type provided to the device meter 125corresponds to an anchor point in the particular reference media thatalso corresponds to the reference signature of the first type that wasdetermined to match the monitored signatures of the first typepreviously generated and reported by the device meter 125. In suchexamples, the device meter 125 generates the monitored signatures of thesecond type from the media presented by the media device 110, andcompares the monitored signatures to the sequence of referencesignatures received from the data processing facility 140. Suchsignature generation and comparison continues (with further referencesignatures of the second type being provided by the data processingfacility 140 as needed to continue the sequence) until the device meter125 determines that a number of monitored signature(s) of the secondtype have failed to match the corresponding reference signature(s) inthe sequence of reference signatures of the second type. When such amatch failure is detected, the device meter 125 sends a match failureindication to the data processing facility 140 to indicate that themonitored signature(s) of the second type are no longer adequatelymatching the sequence of reference signature of the second type. Thedevice meter 125 also reverts to using the signatures of the first typeto identify the new media being presented by the media device 110.

In the preceding examples, the number of monitored signature(s) of thesecond type that result in declaration of a failure has a value, whichis greater than or equal to one, that, for example, can be hardcoded,preconfigured during system initialization, specified during systemoperation as a configuration parameter, etc. In some examples, thenumber is set to a low value to enable fast detection of a matchfailure, whereas in other examples, the number is set to a high value toprovide robustness (e.g., such as when the second type of signature is alight signature that is susceptible to ambient noise, volume changes,etc., at the monitored site 105).

In some examples, the device meter 125 samples the media signal(s)(e.g., an audio signal and/or a video signal) forming the monitoredmedia presentation and sends the media signal samples to the dataprocessing facility 140, which generates and processes the differenttypes of monitored signatures, as described above. Additionally oralternatively, in some examples, the audience measurement system 100combines media monitoring using multiple types of signatures, asdisclosed herein, with other media identification techniques, such asmedia identification based on (a) watermarks/codes embedded or otherwiseincluded with the monitored media, (b) tuning data and/or deviceoperation data obtained by monitoring operation of the media device 110,etc.

A block diagram of an example implementation of the device meter 125 ofFIG. 1 is illustrated in FIG. 2. The example device meter 125 of FIG. 2includes an example media interface 205 to obtain access to one or moremedia signals output by the media device 110. For example, the mediainterface 205 can be implemented by one or more cable connections toelectrically, optically or otherwise communicatively couple with one ormore audio outputs and/or video outputs of the media device 110.Additionally or alternatively, the media interface 205 can beimplemented by one or more audio sensors, such as a microphone, atransducer, etc., capable of non-invasively receiving and processing anaudio signal (e.g., such as an acoustic signal) that is output by themedia device 110. Additionally or alternatively, the media interface 205can be implemented by one or more video sensors, such as a camera, alight detector, etc., capable of non-invasively receiving and processinga video signal (e.g., such as video frames) output by the media device110.

The example device meter 125 of FIG. 2 also includes an examplesignature processor 210 to generate monitored signatures from the mediasignal(s) obtained via the media interface 205. Each monitored signaturegenerated by the signature processor 210 is representative of arespective segment of the media (e.g., corresponding to several secondsof the media) being presented by the media device 110. Examples ofsignature techniques that can be implemented by the signature processor210 include, but are not limited to, any or all of the techniquesdescribed in U.S. Pat. No. 4,677,466 issued to Lert et al. on Jun. 30,1987; U.S. Pat. No. 5,481,294 issued to Thomas et al. on Jan. 2, 1996;U.S. Pat. No. 7,460,684 issued to Srinivasan on Dec. 2, 2008; U.S.Publication No. 2005/0232411 to Srinivasan et al. published on Oct. 20,2005; U.S. Publication No. 2006/0153296 to Deng published on Jul. 13,2006; U.S. Publication No. 2006/0184961 to Lee et al. published on Aug.17, 2006; U.S. Publication No. 2006/0195861 to Lee published on Aug. 31,2006; U.S. Publication No. 2007/0274537 to Srinivasan published on Nov.29, 2007; U.S. Publication No. 2008/0091288 to Srinivasan published onApr. 17, 2008; and U.S. Publication No. 2008/0276265 to Topchy et al.published on Nov. 6, 2008, all of which are hereby incorporated byreference in their respective entireties.

The signature processor 210 of the illustrated example also generatesmultiple types of monitored signatures from the media signal(s) obtainedvia the media interface 205. For example, the signature processor 210can generate monitored signatures of a first type and/or monitoredsignatures of a second type from the monitored media signal(s). Thesignatures of the first type can correspond to rich, high resolutionsignatures, whereas the signatures of the second type can correspond tolight, low resolution signatures, which are smaller than the rich, highresolution signatures of the first type. An example implementation ofthe signature processor 210 of FIG. 2 is illustrated in FIG. 3.

Turning to FIG. 3, the signature processor 210 of the illustratedexample includes an example type-1 signature generator 305 and anexample type-2 signature generator 310. The type-1 signature generator305 generates the monitored signatures of the first type, whereas thetype-2 signature generator 310 generates the monitored signatures of thesecond type. In some examples, the type-1 signature generator 305 andthe type-2 signature generator 310 are implemented by the same physical(e.g., hardware) processor. In such examples, the monitored signaturesof the first type and the monitored signatures of the second type areboth generated by the signature processor 210 using the same signaturingprocedure, but with the signatures of the first type being generatedusing a higher data sampling rate, more bits to represent the sampledmedia signal value, more signal frequencies from which the signaturesare to be generated, etc., than are used when generating the signaturesof the second type. In this way, the monitored signatures of the firsttype are generated to have higher resolution than the monitoredsignatures of the second type and, thus, the monitored signatures of thefirst type are typically larger (e.g., include more bits of data) thanthe monitored signatures of the second type.

In other examples, the type-1 signature generator 305 and the type-2signature generator 310 are implemented by different processingelements. In such examples, the signatures of the first type and thesignatures of the second type can be generated by the signatureprocessor 210 using different signaturing procedures. For example, thetype-1 signature generator 305 can implement a first signaturingprocedure that yields higher resolution and, thus, larger signaturesthan a second signaturing procedure implemented by the type-2 signaturegenerator 310.

The signature processor 210 of FIG. 3 also includes an example signatureinterval adjuster 315 to adjust the interval between monitoredsignatures generated by the type-1 signature generator 305 and/or thetype-2 signature generator 310. In some examples, the signature intervaladjuster 315 is included in the signature processor 210 to enable theintervals between generation of the monitored signatures to be adjustedbased on one or more characteristics of the media signal(s)corresponding to the monitored media presentation. For example, thetype-1 signature generator 305 and the type-2 signature generator 310(or, more generally, the signature processor 210) generate monitoredsignatures from sequentially sampled segments of the monitored mediasignal(s) to enable continuous monitoring of the media presented by themedia device 110. However, in some examples, such as after the monitoredmedia has been identified using the signatures of the first type, thesignature interval adjuster 315 can adjust the sampling interval betweenmonitored signatures of the second type that are generated by the type-2signature generator 310 based on characteristics of the monitored mediasignal. For example, if the signature interval adjuster 315 determinesthat strong audio and/or video signals have been obtained from themonitored media device 110, then the signature interval adjuster 315 canincrease the interval between the monitored signatures of the secondtype (or, in other words, decrease the sampling rate) to improve theoperating efficiency of the signature processor 210. However, if thesignature interval adjuster 315 determines that weak and/or noisy audioand/or video signals have been obtained from the monitored media device110, then the signature interval adjuster 315 can decrease the intervalbetween the monitored signatures of the second type (or, in other words,increase the sampling rate) to improve signature matching accuracy. Insome examples, to support variable intervals between signatures, thesignature processor 210 associates timestamps with the monitoredsignatures to enable comparison of the monitored signatures with therespective reference signatures that are representative of the segmentsin the reference media that correspond to the segments of the monitoredmedia that were used to generate the monitored signatures.

Returning to FIG. 2, the device meter 125 of the illustrated examplealso includes an example controller 215 to control operation of thesignature processor 210. For example, the controller 215 causes thesignature processor 210 to switch among generation of monitoredsignatures of different types. In some examples, the controller 215configures the signature processor 210 to generate monitored signaturesof a first type until the monitored media has been identified (e.g.,which may correspond to receipt of a match success indication from thedata processing facility 140). After the monitored media is identified,the controller 215 configures the signature processor 210 to generatemonitored signatures of a second type to enable continuous monitoring ofthe media. In some examples, the controller 215 later configures thesignature processor 210 to revert to generating monitored signatures ofthe first type when the monitored signatures of the second type are nolonger able to identify the monitored media (which may correspond toreceipt of a match failure indication from the data processing facility140 or detection of a match failure by the device meter 125, whichindicates that the particular reference media that was previouslyidentified as matching the monitored media no longer correspond to themedia being monitored by the device meter 125). The controller 215 canthen continue cycling between configuring the signature processor 210 togenerate monitored signatures of the first type vs. monitored signaturesof the second type depending upon whether the monitored media stillmatches a particular, previously identified reference media source.

To report the monitored signatures generated by the signature processor210 to the data processing facility 140, the example device meter 125 ofFIG. 2 includes an example signature reporter 220. The signaturereporter 220 retrieves the monitored signatures generated by thesignature processor 210 and formats the monitored signatures into anyappropriate data format according to any appropriate protocol forsending to the data processing facility 140 via an example networkinterface 225. The network interface 225 is implemented using anynetworking technology capable of interfacing with the network 135 andcapable of sending data to and receiving data from the data processingfacility 140.

In the illustrated example of FIG. 2, the device meter 125 includes anexample data receiver 230 to receive one or more indications from thedata processing facility 140 that indicate whether monitored signaturesreported by the device meter 125 have been determined to successfullymatch or fail to match reference signatures associated with one or morereference sources known to the audience measurement system 100. Forexample, the data receiver 230 may receive a match success indicationfrom the data processing facility 140 when at least one of the monitoredsignatures of the first type that were previously generated and reportedby the device meter 125 have been determined to match at least onereference signature corresponding to a particular reference media sourcefrom a collection of reference media known to the data processingfacility 140. As such, the received match success indication can be usedby the device meter 125 to infer that the media being monitored has beenidentified by the data processing facility 140.

In some examples, after the data processing facility 140 sends the matchsuccess indication to the device meter 125 (which is received by thedata receiver 230), the data processing facility 140 also sends asequence of reference signatures of the second type to the device meter125, which are also received by the data receiver 230. For example, thesequence of reference signatures of the second type can correspond tothe particular reference media source previously identified as matchingthe monitored media (e.g., via a successful match between at least onepreviously reported monitored signature of the first type and acorresponding reference signature of the first type that is associatedwith the particular reference media source). In such examples, thedevice meter 125 of FIG. 2 also includes an example comparator 235 tocompare the received sequence of reference signatures of the second typewith the monitored signatures of the second type that are generated bythe signature processor 210. For example, the comparator 235 can be usedto compare a monitored signature representative of a particular segmentof the monitored media with a reference signature corresponding to asimilar point in the identified reference media (e.g., by comparingtimestamps associated with the monitored signatures and the referencesignatures). The comparator 235 can implement any type(s) and/or numberof comparison criteria, such as a cross-correlation value, a Hammingdistance, etc., to determine whether a monitored signature and areference signature match or substantially match within a particulartolerance level (e.g., which may be predetermined, specified as aconfiguration parameter or input, etc.).

In some examples, the received sequence of the reference signatures ofthe second type has a starting reference signature that isrepresentative of an anchor point in the identified reference media thatcorresponds to the segment of the reference media represented by thereference signature of the first type that matched the previouslyreported monitored signature of the first type (and, thus, caused theparticular reference media to be identified as corresponding to themonitored media). In some examples, device meter 125 continues toreceive successive sequences of reference signatures of the second type(e.g., each sequence corresponding to some duration of the referencemedia, such a several minutes of the reference media) so long as thecomparator 235 determines that the reference signatures of the secondtype continue to match the monitored signatures of the second type (and,thus, the monitored media still corresponds to the identified referencemedia). However, when the comparator 235 determines that a number (e.g.,greater than or equal to one) of monitored signatures of the second typedo not match the corresponding reference signatures of the second type(and, thus, the monitored media no longer matches the previouslyidentified reference media), the comparator 235 causes an example datareporter 240 included in the device meter 125 to send a match failureindication, via the network interface 225, to the data processingfacility 140. In some examples, the data reporter 240 may includefurther descriptive data associated with the match failures, such as atimestamp indicating the point in the monitored media at which themonitored signatures of the second type no longer matched thecorresponding reference signatures of the second type (and, thus, thepoint in the monitored media at which the previously identifiedreference media no longer matched the monitored media).

In some examples, the device meter 125 does not include the comparator235 and, thus, does not perform the comparison of the monitoredsignatures of the second type with the reference signatures of thesecond type. In such examples, the signature reported 220 of the devicemeter 125 is also used to report the monitored signatures of the secondtype generated by the signature processor 210 to the data processingfacility 140 (e.g., via the network interface 225). In such examples,the data processing facility 140 compares the monitored signatures ofthe second type with the reference signatures of the second type, andsends the match failure indication to the device meter 125 (e.g., whichis received by the data receiver 230 via the network interface 225),which indicates that monitored signatures of the second type no longermatch the reference signatures of the second type.

The example device meter 125 of FIG. 2 also includes an example memory245 to store the monitored signatures of the first and second types thatare generated by the signature processor 210. In some examples, thememory 245 also stores the sequence(s) of reference signatures of thesecond type that is(are) received from the data processing facility 140.The memory 245 may be implemented by any type of a storage or memorydevice, a database, etc., such as the mass storage device 1130 and/orthe volatile memory 1118 included in the example processing system 1100of FIG. 11, which is described in greater detail below.

A block diagram of an example data facility processor 400 that may beused to implement signature processing in the example data processingfacility 140 of FIG. 1 is illustrated in FIG. 4. The example datafacility processor 400 of FIG. 4 includes an example network interface405 implemented using any networking technology capable of interfacingwith the network 135 and capable of sending data to and receiving datafrom the device meter 125. The example data facility processor 400 ofFIG. 4 also includes an example signature receiver 410 to receive, viathe network interface 405, the monitored signatures reported by thedevice meter 125 in any appropriate data format according to anyappropriate protocol. The example data facility processor 400 of FIG. 4further includes an example comparator 415 to compare the monitoredsignatures received from the device meter 125 with reference signaturesrepresentative of the collection of reference media known to the dataprocessing facility 140. Similar to the comparator 235 of FIG. 2, thecomparator 415 of FIG. 4 can implement any type(s) and/or number ofcomparison criteria, such as a cross-correlation value, a Hammingdistance, etc., to determine whether a monitored signature and areference signature match or substantially match within a particulartolerance level (e.g., which may be predetermined, specified as aconfiguration parameter or input, etc.).

For example, the signature receiver 410 can receive the monitoredsignatures of the first type (e.g., the rich or high resolutionmonitored signatures), as described above, for comparison with referencesignatures of the first type that are associated with reference mediasources known to the data processing facility 140. In such examples, thecomparator 415 compares the monitored signatures of the first type withthe reference signatures of the first type to identify a match. When amonitored signature of the first type is determined to match a referencesignature of the first type, the comparator 415 causes an exampleindication processor 420 included in the data facility processor 400 tosend a match success indication, via the network interface 405, to thedevice meter 125. The comparator 415 also identifies the particularreference media represented by the matching reference signature ascorresponding to the monitored media represented by the monitoredsignatures of the first type that have been received from the devicemeter 125.

In some examples, after the comparator 415 identifies the particularreference media corresponding to the monitored media, the data facilityprocessor 400 also provides sequence(s) of reference signatures of asecond type (e.g., the light or low resolution reference signatures) tothe device meter 125 to enable continues monitoring of the nowidentified media being presented by the media device 110, as describedabove. In such examples, the data facility processor 400 includes anexample signature provider 425 to provide the sequence(s) of referencesignatures of the second type, via the network interface 405, to thedevice meter 125. The signature provider 425 can format the referencesignatures using any appropriate data format for sending via anyappropriate data protocol. In such examples, the signature provider 425continues to provide successive sequences of reference signatures of thesecond type to the device meter 125 until a match failure indication isreceived by the indication processor 420 from the device meter 125(e.g., which indicates that the previously identified reference mediacorresponding the reference signatures of the second type no longercorresponds to the media being monitored by the device meter 125).

In some examples, after the comparator 415 identifies the particularreference media corresponding to the monitored media and the indicationprocessor sends the match success indication to the device meter, thedata facility processor 400 receives the monitored signatures of thesecond type from the device meter, as described above. In such examples,the comparator 415 compares the monitored signatures of the second typewith the sequence of reference signatures of the second type thatcorrespond to the previously identified reference media (e.g., such asby using the processing described above in connection with thecomparator 235 of FIG. 2). In such examples, the comparator 415continues to compare the received, monitored signatures of the secondtype with the sequence of reference signatures of the second type untilthe comparator 235 determines that a number (e.g., greater than or equalto one) of monitored signatures of the second type do not match thecorresponding reference signatures of the second type (and, thus, themonitored media no longer matches the previously identified referencemedia). When this occurs, the comparator 415 causes the indicationprocessor 420 to send a match failure indication, via the networkinterface 225, to the device meter 125 (e.g., which cause the devicemeter 125 to switch to generating and reporting monitored signatures ofthe first type to enable identification of a different reference mediasource corresponding to the new (e.g., changed) media being monitored bythe device meter 125).

The data facility processor 400 of FIG. 4 also includes an examplememory 430 to store the reference signatures of the first and secondtypes that are used for comparison with the monitored signatures of thefirst and second types that are generated by the device meter 125. Insome examples, the memory 430 also stores the monitored signatures ofthe first and second types that are received from the device meter 125.The memory 430 may be implemented by any type of a storage or memorydevice, a database, etc., such as the mass storage device 1130 and/orthe volatile memory 1118 included in the example processing system 1100of FIG. 11, which is described in greater detail below.

While example manners of implementing the audience measurement system100 have been illustrated in FIGS. 1-4, one or more of the elements,processes and/or devices illustrated in FIGS. 1-4 may be combined,divided, re-arranged, omitted, eliminated and/or implemented in anyother way. Further, the example device meter 125, the example dataprocessing facility 140, the example media interface 205, the examplesignature processor 210, the example controller 215, the examplesignature reporter 220, the example network interface 225, the exampledata receiver 230, the example comparator 235, the example data reporter240, the example type-1 signature generator 305, the example type-2signature generator 310, the example signature interval adjuster 315,the example data facility processor 400, the example network interface405, the example signature receiver 410, the example comparator 415, theexample indication processor 420, the example signature provider 425and/or, more generally, the example audience measurement system 100 maybe implemented by hardware, software, firmware and/or any combination ofhardware, software and/or firmware. Thus, for example, any of theexample device meter 125, the example data processing facility 140, theexample media interface 205, the example signature processor 210, theexample controller 215, the example signature reporter 220, the examplenetwork interface 225, the example data receiver 230, the examplecomparator 235, the example data reporter 240, the example type-1signature generator 305, the example type-2 signature generator 310, theexample signature interval adjuster 315, the example data facilityprocessor 400, the example network interface 405, the example signaturereceiver 410, the example comparator 415, the example indicationprocessor 420, the example signature provider 425 and/or, moregenerally, the example audience measurement system 100 could beimplemented by one or more circuit(s), programmable processor(s),application specific integrated circuit(s) (ASIC(s)), programmable logicdevice(s) (PLD(s)) and/or field programmable logic device(s) (FPLD(s)),etc. When any of the apparatus or system claims of this patent are readto cover a purely software and/or firmware implementation, at least oneof the example audience measurement system 100, the example device meter125, the example data processing facility 140, the example mediainterface 205, the example signature processor 210, the examplecontroller 215, the example signature reporter 220, the example networkinterface 225, the example data receiver 230, the example comparator235, the example data reporter 240, the example type-1 signaturegenerator 305, the example type-2 signature generator 310, the examplesignature interval adjuster 315, the example data facility processor400, the example network interface 405, the example signature receiver410, the example comparator 415, the example indication processor 420and/or the example signature provider 425 are hereby expressly definedto include a tangible computer readable medium such as a memory, digitalversatile disk (DVD), compact disk (CD), Blu-ray disc™, etc., storingsuch software and/or firmware. Further still, the example audiencemeasurement system 100 of FIGS. 1-4 may include one or more elements,processes and/or devices in addition to, or instead of, thoseillustrated in FIGS. 1-4, and/or may include more than one of any or allof the illustrated elements, processes and devices.

Flowcharts representative of example machine readable instructions forimplementing the example audience measurement system 100, the exampledevice meter 125, the example data processing facility 140, the examplemedia interface 205, the example signature processor 210, the examplecontroller 215, the example signature reporter 220, the example networkinterface 225, the example data receiver 230, the example comparator235, the example data reporter 240, the example type-1 signaturegenerator 305, the example type-2 signature generator 310, the examplesignature interval adjuster 315, the example data facility processor400, the example network interface 405, the example signature receiver410, the example comparator 415, the example indication processor 420and/or the example signature provider 425 are shown in FIGS. 5-10. Inthese examples, the machine readable instructions represented by eachflowchart may comprise one or more programs for execution by aprocessor, such as the processor 1112 shown in the example processingsystem 1100 discussed below in connection with FIG. 11. The one or moreprograms, or portion(s) thereof, may be embodied in software stored on atangible computer readable medium such as a CD-ROM, a floppy disk, ahard drive, a digital versatile disk (DVD), a Blu-ray discTM, or amemory associated with the processor 1112, but the entire program orprograms and/or portions thereof could alternatively be executed by adevice other than the processor 1112 (e.g., such as a controller and/orany other suitable device) and/or embodied in firmware or dedicatedhardware (e.g., implemented by an ASIC, a PLD, an FPLD, discrete logic,etc.). Also, one or more of the machine readable instructionsrepresented by the flowchart of FIGS. 5-10 may be implemented manually.Further, although the example machine readable instructions aredescribed with reference to the flowcharts illustrated in FIGS. 5-10,many other methods of implementing the example audience measurementsystem 100, the example device meter 125, the example data processingfacility 140, the example media interface 205, the example signatureprocessor 210, the example controller 215, the example signaturereporter 220, the example network interface 225, the example datareceiver 230, the example comparator 235, the example data reporter 240,the example type-1 signature generator 305, the example type-2 signaturegenerator 310, the example signature interval adjuster 315, the exampledata facility processor 400, the example network interface 405, theexample signature receiver 410, the example comparator 415, the exampleindication processor 420 and/or the example signature provider 425 mayalternatively be used. For example, with reference to the flowchartsillustrated in FIGS. 5-10, the order of execution of the blocks may bechanged, and/or some of the blocks described may be changed, eliminated,combined and/or subdivided into multiple blocks.

As mentioned above, the example processes of FIGS. 5-10 may beimplemented using coded instructions (e.g., computer readableinstructions) stored on a tangible computer readable medium such as ahard disk drive, a flash memory, a read-only memory (ROM), a CD, a DVD,a cache, a random-access memory (RAM) and/or any other storage media inwhich information is stored for any duration (e.g., for extended timeperiods, permanently, brief instances, for temporarily buffering, and/orfor caching of the information). As used herein, the term tangiblecomputer readable medium is expressly defined to include any type ofcomputer readable storage and to exclude propagating signals.Additionally or alternatively, the example processes of FIGS. 5-10 maybe implemented using coded instructions (e.g., computer readableinstructions) stored on a non-transitory computer readable medium, suchas a flash memory, a ROM, a CD, a DVD, a cache, a random-access memory(RAM) and/or any other storage media in which information is stored forany duration (e.g., for extended time periods, permanently, briefinstances, for temporarily buffering, and/or for caching of theinformation). As used herein, the term non-transitory computer readablemedium is expressly defined to include any type of computer readablemedium and to exclude propagating signals. Also, as used herein, theterms “computer readable” and “machine readable” are consideredequivalent unless indicated otherwise. Furthermore, as used herein, whenthe phrase “at least” is used as the transition term in a preamble of aclaim, it is open-ended in the same manner as the term “comprising” isopen ended. Thus, a claim using “at least” as the transition term in itspreamble may include elements in addition to those expressly recited inthe claim.

Example machine readable instructions 500 that may be executed toimplement the example audience measurement system 100 of FIG. 1 arerepresented by the flowchart shown in FIG. 5. With reference to thepreceding figures, the machine readable instructions 500 of FIG. 5 beginexecution at block 505 at which the device meter 125 and the dataprocessing facility 140 of the audience measurement system 100 usemonitored and reference signatures of a first type (e.g., correspondingto rich, high-resolution signatures) for monitoring media beingpresented by the media device 110 until at least one monitored signatureis determined to match a reference signature, as described above. Atblock 510, the device meter 125 and the data processing facility 140determine whether a successful match has occurred and, thus, themonitored media can be identified as corresponding to the particularreference media, from the collection of reference media, that isrepresented by the matching reference signature of the first type.

If a successful match has occurred (block 510), then at block 515 thedevice meter 125 and the data processing facility 140 use monitored andreference signatures of a second type (e.g., corresponding to light,low-resolution signatures) for monitoring the media being presented bythe media device 110 until at a number of monitored signatures fail tomatch their corresponding reference signatures. As described above, thereference signatures of the second type represent the particularreference media that was previously identified as corresponding to themonitored media. At block 520, the device meter 125 and the dataprocessing facility 140 determine whether the number of monitoredsignatures fail have failed to match their corresponding referencesignatures and, thus, the media being presented by the media device 110no longer corresponds to the previously identified reference media. Asdescribed above, the number of monitored signatures used to determinewhether a match failure has occurred is greater than or equal to one,and may be hard-coded, preconfigured, specified, etc.

If a match failure has occurred (block 520), then at block 525 thedevice meter 125 and the data processing facility 140 revert to usingthe monitored and reference signatures of the first type (e.g.,corresponding to rich, high-resolution signatures) for monitoring themedia being presented by the media device 110 (e.g., to enable thenew/changed media to be initially identified). Accordingly, processingreturns to block 505 and blocks subsequent thereto to enable signatureprocessing to revert to using the monitored and reference signatures ofthe first type.

First example machine readable instructions 600 that may be executed toimplement the example device meter 125 of FIGS. 1-3 are represented bythe flowchart shown in FIG. 6. With reference to the preceding figures,the machine readable instructions 600 of FIG. 6 begin execution at block605 at which the signature processor 210 of the device meter 125processes the media signal(s) forming the media being presented by themedia device 110 to obtain (e.g., generate) monitored signatures of afirst type (e.g., the rich, high resolution signatures). At block 610,the signature reporter 220 of the device meter 125 reports the monitoredsignatures of the first type to the data processing facility 140 forcomparison with reference signatures of the first type that represent acollection of reference media sources known to the audience measurementsystem 100. At block 615, the data receiver 230 of the device meter 125monitors for receipt of a match success indication, which indicates thatat least one monitored signature of the first type has matched areference signature of the first type. If a match success indication isreceived (block 615), then at block 620 the controller 215 of the devicemeter 125 causes the signature processor 210 to halt the processing toobtain monitored signatures of the first type (e.g., because themonitored media has been identified as corresponding to the particularreference media represented by the matching reference signature). Asillustrated in FIG. 6, the processing at blocks 605 through 620corresponds to the processing at block 505 of FIG. 5.

At block 625 of FIG. 6, the data receiver 230 receives a sequence ofreference signatures of a second type (e.g., the light, low resolutionsignatures) that correspond (e.g., represent) the matching referencemedia previously identified using the signatures of the first type. Atblock 630, the signature processor 210 processes the media signal(s)forming the media being presented by the media device 110 to obtain(e.g., generate) monitored signatures of the second type. At block 635,the comparator 235 of the device meter 125 compares the monitoredsignatures of the second type with the sequence of reference signaturesof the second type until a match failure is detected. At block 640, thecomparator 235 determines whether the match failure has been detected.As described above, a match failure can correspond to a number ofmonitored signatures of the second type failing to match theircorresponding reference signatures of the second type. If the matchfailure is detected (block 640), then at block 645 the controller 215causes the signature processor 210 to halt the processing to obtainmonitored signatures of the second type (e.g., because the monitoredmedia has been determined to no longer correspond to the previouslymatching reference media). At block 645, the data reporter 240 of thedevice meter 125 also reports a match failure indication and anyassociated information to the data processing facility 140, whichindicates that the monitored media has been determined to no longercorrespond to the previously matching reference media. Processing thenreturns to blocks 605 and blocks subsequent thereto to enable signatureprocessing to revert to using the signatures of the first type toinitially identify the new/changed media being presented by the mediadevice 110. As illustrated in FIG. 6, the processing at blocks 625through 645 corresponds to the processing at block 515 of FIG. 5.

Second example machine readable instructions 700 that may be executed toimplement the example device meter 125 of FIGS. 1-3 are represented bythe flowchart shown in FIG. 7. FIG. 7 includes blocks 605-620 and 630from FIG .6. Accordingly, the processing performed by the examplemachine readable instructions 700 at these blocks is described in detailabove in connection with the discussion of FIG. 6 and, in the interestof brevity, is not repeated in the discussion of FIG. 7.

With reference to the preceding figures, the machine readableinstructions 700 of FIG. 7 begin execution at block 605 and perform theprocessing at blocks 605 through 620 and 630 as described above inconnection with the description of the machine readable instructions 600of FIG. 6. Thus, at this point in the machine readable instructions 700,the signature processor 210 of the device meter 125 is obtaining (e.g.,generating) monitored signatures of the second type for comparison withreference signatures of the second type that correspond to (e.g.,represent) the particular reference media previously identified asmatching the media being monitored by the device meter 125. At block705, the signature reporter 220 of the device meter 125 reports themonitored signatures of the second type to the data processing facility140 for comparison with the sequence of reference signatures of thesecond type that represent the previously identified, matching referencemedia source. At block 710, the data receiver 230 of the device meter125 monitors for receipt of a match failure indication, which indicatesthat a number of monitored signatures of the second type have failed tomatch their corresponding reference signatures of the second type. Ifthe match failure indication is received (block 615), then at block 620the controller 215 of the device meter 125 causes the signatureprocessor 210 to halt the processing to obtain monitored signatures ofthe second type (e.g., because the monitored media has been determinedto no longer correspond to the previously matching reference media).Processing then returns to blocks 605 and blocks subsequent thereto toenable signature processing to revert to using the signatures of thefirst type to initially identify the new/changed media being presentedby the media device 110. As illustrated in FIG. 7, the processing atblocks 630 and 705 through 715 corresponds to the processing at block515 of FIG. 5.

First example machine readable instructions 800 that may be executed toimplement the example data facility processor 400 of the example dataprocessing facility 140 of FIGS. 1 and 4 are represented by theflowchart shown in FIG. 8. With reference to the preceding figures, themachine readable instructions 800 of FIG. 8 begin execution at block 805at which the signature receiver 410 of the data facility processor 400receives monitored signatures of a first type (e.g., the rich, highresolution signatures) from the device meter 125, which arerepresentative of the media being presented by the media device 110. Atblock 810, the comparator 415 of the data facility processor 400compares the received, monitored signatures of the first type withreference signatures of the first type that are representative of acollection of reference media sources known to the data processingfacility 140. At block 815, the comparator 415 determines whether amatch between the monitored signatures of the first type and thereference signatures of the first type has been found. If a match hasbeen found and, thus, the matching reference media can be used toidentify the media being monitored by the device meter 125 (block 815),then at block 820 the indication processor 420 of the data facilityprocessor 400 sends a match success indication to the device meter 125(e.g., which causes the device meter 125 to switch to generating andreporting monitored signatures of a different type). As illustrated inFIG. 8, the processing at blocks 805 through 820 corresponds to theprocessing at block 505 of FIG. 5.

At block 825, the signature provider 425 of the data facility processor400 sends sequence(s) of reference signatures of a second type (e.g.,the light, low resolution signatures) to the device meter 125 forcomparison with monitored signatures of the first type. As describedabove, the sequence(s) of reference signatures of the second type arerepresentative of the matching reference media previously identified ascorresponding to the media being monitored by the device meter 125. Atblock 830, the indication processor 420 monitors for receipt of a matchfailure indication, which indicates that the reference signatures of thesecond type no longer match the monitored signatures of the second typebeing generated by the device meter 125 and, thus, the monitored mediano longer corresponds to previously identified, matching referencemedia. If the match failure indication is received (block 835), then atblock 840 the indication processor 420 also receives and processesdescriptive information for the match failure, such as a timestampindicating when the failure was detected, to enable proper crediting ofthe monitored media (e.g., such as by determining the duration of timeover which the monitored media corresponded to the previously matchingreference media). Processing then returns to blocks 805 and blockssubsequent thereto to enable signature processing to revert to using thesignatures of the first type to initially identify the new/changed mediabeing presented by the media device 110. As illustrated in FIG. 8, theprocessing at blocks 825 through 840 corresponds to the processing atblock 515 of FIG. 5.

Second example machine readable instructions 900 that may be executed toimplement the example data facility processor 400 of the example dataprocessing facility 140 of FIGS. 1 and 4 are represented by theflowchart shown in FIG. 9. FIG. 9 includes blocks 805 through 820 fromFIG .8. Accordingly, the processing performed by the example machinereadable instructions 900 at these blocks is described in detail abovein connection with the discussion of FIG. 8 and, in the interest ofbrevity, is not repeated in the discussion of FIG. 9.

With reference to the preceding figures, the machine readableinstructions 900 of FIG. 9 begin execution at block 805 and perform theprocessing at blocks 805 through 820 as described above in connectionwith the description of the machine readable instructions 800 of FIG. 8.Thus, at this point in the machine readable instructions 900, the datafacility processor 400 has used the signatures of the first type toidentify matching reference media that corresponds to the media beingpresented at the monitored site 105 by the media device 110 and that isbeing monitored by the device meter 125. Next, at block 905, thesignature receiver 410 of the data facility processor 400 receivesmonitored signatures of the second type from the device meter 125, whichare representative of the media being presented by the media device 110.At block 910, the comparator 415 of the data facility processor 400compares the monitored signatures of the second type with a sequence ofreference signatures of the second type that are representative of thematching reference media previously identified as corresponding to themedia being monitored by the device meter 125.

At block 915, the comparator 415 determines whether a match failure hasbeen detected. As described above, the match failure can correspond to anumber of monitored signatures of the second type failing to match theircorresponding reference signatures of the second type. If the matchfailure is detected (block 915), then at block 920 the indicationprocessor 420 of the data facility processor 400 sends a match failureindication to the device meter 125, which indicates that the monitoredmedia has been determined to no longer correspond to the previouslymatching reference media. Processing then returns to blocks 805 andblocks subsequent thereto to enable signature processing to revert tousing the signatures of the first type to initially identify thenew/changed media being presented by the media device 110. Asillustrated in FIG. 9, the processing at blocks 905 through 920corresponds to the processing at block 515 of FIG. 5.

Example machine readable instructions 1000 that may be executed toimplement the example signature interval adjuster 315 of the examplesignature processor 210 of FIGS. 2 and/or 3 are represented by theflowchart shown in FIG. 10. With reference to the preceding figures, themachine readable instructions 1000 of FIG. 10 begin execution at block1005 at which the signature interval adjuster 315 measurescharacteristic(s) of the media signal(s) being output by the mediadevice 110 and that are being monitored by the device meter 125. Forexample, the signature interval adjuster 315 can measure signal strength(e.g., such as in terms of signal power, signal energy, signal volume,signal amplitude, etc.), signal-to-noise ratio, noise content, etc. Atblock 1010, the signature interval adjuster 315 adjusts the samplinginterval between monitored signatures of the second type (e.g., thelight, low resolution signatures) that are generated by the signatureprocessor 210 (e.g., by the type 2 signature generator 310 of thesignature processor 210). For example, the signature interval adjuster315 can increase the interval between the monitored signatures of thesecond type (or, in other words, decrease the sampling rate) when themeasured characteristic(s) indicate that the monitored media signal(s)is(are) strong and/or are not noisy, but can decrease the intervalbetween the monitored signatures of the second type (or, in other words,increase the sampling rate) when the measured characteristic(s) indicatethat the monitored media signal(s) is(are) weak and/or are noisy.Processing returns to block 1005 and blocks subsequent thereto to enablethe signature interval adjuster 315 to continue to adjust the samplingintervals between the monitored signatures based on the measuredcharacteristic(s) of the monitored media signal(s).

FIG. 11 is a block diagram of an example processing system 1100 capableof executing the instructions of FIGS. 5-10 to implement the exampleaudience measurement system 100, the example device meter 125, theexample data processing facility 140, the example media interface 205,the example signature processor 210, the example controller 215, theexample signature reporter 220, the example network interface 225, theexample data receiver 230, the example comparator 235, the example datareporter 240, the example type-1 signature generator 305, the exampletype-2 signature generator 310, the example signature interval adjuster315, the example data facility processor 400, the example networkinterface 405, the example signature receiver 410, the examplecomparator 415, the example indication processor 420 and/or the examplesignature provider 425 of FIGS. 1-4. The processing system 1100 can be,for example, a server, a personal computer, a mobile phone (e.g., asmartphone, a cell phone, etc.), a personal digital assistant (PDA), anInternet appliance, a DVD player, a CD player, a digital video recorder,a Blu-ray player, a gaming console, a personal video recorder, a set topbox, a digital camera, or any other type of computing device.

The system 1100 of the instant example includes a processor 1112. Forexample, the processor 1112 can be implemented by one or moremicroprocessors and/or controllers from any desired family ormanufacturer.

The processor 1112 includes a local memory 1113 (e.g., a cache) and isin communication with a main memory including a volatile memory 1114 anda non-volatile memory 1116 via a bus 1118. The volatile memory 1114 maybe implemented by Static Random Access Memory (SRAM), SynchronousDynamic Random Access Memory (SDRAM), Dynamic Random Access Memory(DRAM), RAMBUS Dynamic Random Access Memory (RDRAM) and/or any othertype of random access memory device. The non-volatile memory 1116 may beimplemented by flash memory and/or any other desired type of memorydevice. Access to the main memory 1114, 1116 is controlled by a memorycontroller.

The processing system 1100 also includes an interface circuit 1120. Theinterface circuit 1120 may be implemented by any type of interfacestandard, such as an Ethernet interface, a universal serial bus (USB),and/or a PCI express interface.

One or more input devices 1122 are connected to the interface circuit1120. The input device(s) 1122 permit a user to enter data and commandsinto the processor 1112. The input device(s) can be implemented by, forexample, a keyboard, a mouse, a touchscreen, a track-pad, a trackball, atrackbar (such as an isopoint), a voice recognition system and/or anyother human-machine interface.

One or more output devices 1124 are also connected to the interfacecircuit 1120. The output devices 1124 can be implemented, for example,by display devices (e.g., a liquid crystal display, a cathode ray tubedisplay (CRT)), a printer and/or speakers. The interface circuit 1120,thus, typically includes a graphics driver card.

The interface circuit 1120 also includes a communication device, such asa modem or network interface card, to facilitate exchange of data withexternal computers via a network 1126 (e.g., an Ethernet connection, adigital subscriber line (DSL), a telephone line, coaxial cable, acellular telephone system, etc.).

The processing system 1100 also includes one or more mass storagedevices 1128 for storing machine readable instructions and data.Examples of such mass storage devices 1128 include floppy disk drives,hard drive disks, compact disk drives and digital versatile disk (DVD)drives. In some examples, the mass storage device 1130 may implement thememory 245 and/or the memory 430. Additionally or alternatively, in someexamples the volatile memory 1118 may implement the memory 245 and/orthe memory 430.

Coded instructions 1132 corresponding to the instructions of FIGS. 5-10may be stored in the mass storage device 1128, in the volatile memory1114, in the non-volatile memory 1116, in the local memory 1113 and/oron a removable storage medium, such as a CD or DVD 1136.

As an alternative to implementing the methods and/or apparatus describedherein in a system such as the processing system of FIG. 11, the methodsand or apparatus described herein may be embedded in a structure such asa processor and/or an ASIC (application specific integrated circuit).

Finally, although certain example methods, apparatus and articles ofmanufacture have been described herein, the scope of coverage of thispatent is not limited thereto. On the contrary, this patent covers allmethods, apparatus and articles of manufacture fairly falling within thescope of the appended claims either literally or under the doctrine ofequivalents.

What is claimed is:
 1. A media monitoring apparatus comprising: anindication processor to send a first indication to a device meter toindicate that media monitored by the device meter corresponds to firstreference media in response to determining that a media signature of afirst type reported by the device meter matched a reference signature ofthe first type associated with the first reference media, the indicationprocessor to later receive a second indication from the device meterindicating that the media monitored by the device meter no longercorresponds to the first reference media; a signature provider to send aset of reference signatures of a second type associated with the firstreference media to the device meter in response to determining that themedia signature of the first type reported by the device meter matchedthe reference signature of the first type associated with the firstreference media; and a comparator to process subsequent media signaturesof the first type reported by the device meter to identify the mediabeing monitored by the device meter in response to receiving the secondindication.
 2. The apparatus of claim 1, wherein the reference signatureof the first type has higher resolution than respective ones of thereference signatures of the second type.
 3. The apparatus of claim 1,wherein the reference signature of the first type includes more bitsthan respective ones of the reference signatures of the second type. 4.The apparatus of claim 1, wherein the comparator is further to comparethe media signature of the first type with the reference signature ofthe first type associated with the first reference media.
 5. Theapparatus of claim 1, wherein the comparator is further to compare afirst one of the subsequent media signatures of the first type reportedby the device meter with a reference signature of the first typeassociated with second reference media to determine whether the mediamonitored by the device meter corresponds to the second reference media.6. The apparatus of claim 5, wherein the indication processor is furtherto send a third indication to the device meter to indicate that themedia monitored by the device meter corresponds to the second referencemedia in response to the comparator determining that the first one ofthe subsequent media signatures of the first type reported by the devicemeter matched the reference signature of the first type associated withthe second reference media.
 7. The apparatus of claim 5, wherein thesignature provider is further to send a set of reference signatures ofthe second type associated with the second reference media to the devicemeter in response to the comparator determining that the first one ofthe subsequent media signatures of the first type reported by the devicemeter matched the reference signature of the first type associated withthe second reference media.
 8. A media monitoring method comprising: inresponse to determining that a media signature of a first type reportedby a device meter matched a reference signature of the first typeassociated with first reference media, sending, by executing aninstruction with a processor, a first indication to the device meter toindicate that media monitored by the device meter corresponds to thefirst reference media, and sending, by executing an instruction with aprocessor, a set of reference signatures of a second type associatedwith the first reference media to the device meter; receiving a secondindication from the device meter indicating that the media monitored bythe device meter no longer corresponds to the first reference media; andin response to receiving the second indication, processing, with theprocessor, subsequent media signatures of the first type reported by thedevice meter to identify the media being monitored by the device meter.9. The method of claim 8, wherein the reference signature of the firsttype has higher resolution than respective ones of the referencesignatures of the second type.
 10. The method of claim 8, wherein thereference signature of the first type includes more bits than respectiveones of the reference signatures of the second type.
 11. The method ofclaim 8, further including compare the media signature of the first typewith the reference signature of the first type associated with the firstreference media.
 12. The method of claim 8, further including comparinga first one of the subsequent media signatures of the first typereported by the device meter with a reference signature of the firsttype associated with second reference media to determine whether themedia monitored by the device meter corresponds to the second referencemedia.
 13. The method of claim 12, further including sending a thirdindication to the device meter to indicate that the media monitored bythe device meter corresponds to the second reference media in responseto determining that the first one of the subsequent media signatures ofthe first type reported by the device meter matched the referencesignature of the first type associated with the second reference media.14. The method of claim 12, further including sending a set of referencesignatures of the second type associated with the second reference mediato the device meter in response to determining that the first one of thesubsequent media signatures of the first type reported by the devicemeter matched the reference signature of the first type associated withthe second reference media.
 15. A non-transitory computer readablemedium comprising computer readable instructions that, when executed bya processor, cause the processor to at least: in response to determiningthat a media signature of a first type reported by a device metermatched a reference signature of the first type associated with firstreference media, send a first indication to the device meter to indicatethat media monitored by the device meter corresponds to the firstreference media, and send a set of reference signatures of a second typeassociated with the first reference media to the device meter; receive asecond indication from the device meter indicating that the mediamonitored by the device meter no longer corresponds to the firstreference media; and in response to receiving the second indication,process subsequent media signatures of the first type reported by thedevice meter to identify the media being monitored by the device meter.16. The non-transitory computer readable medium of claim 15, wherein thereference signature of the first type has higher resolution thanrespective ones of the reference signatures of the second type.
 17. Thenon-transitory computer readable medium of claim 15, wherein thereference signature of the first type includes more bits than respectiveones of the reference signatures of the second type.
 18. Thenon-transitory computer readable medium of claim 15, wherein theinstructions, when executed, further cause the processor to compare afirst one of the subsequent media signatures of the first type reportedby the device meter with a reference signature of the first typeassociated with second reference media to determine whether the mediamonitored by the device meter corresponds to the second reference media.19. The non-transitory computer readable medium of claim 18, wherein theinstructions, when executed, further cause the processor to send a thirdindication to the device meter to indicate that the media monitored bythe device meter corresponds to the second reference media in responseto determining that the first one of the subsequent media signatures ofthe first type reported by the device meter matched the referencesignature of the first type associated with the second reference media.20. The non-transitory computer readable medium of claim 18, wherein theinstructions, when executed, further cause the processor to send a setof reference signatures of the second type associated with the secondreference media to the device meter in response to determining that thefirst one of the subsequent media signatures of the first type reportedby the device meter matched the reference signature of the first typeassociated with the second reference media.